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Growth Mechanism and Crystal Form of Potassium Dichromate
Author(s) -
Silber C.,
Breidenstein B.,
Heide G.,
Follner H.
Publication year - 1999
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/(sici)1521-4079(199909)34:8<969::aid-crat969>3.0.co;2-t
Subject(s) - potassium dichromate , mechanism (biology) , potassium , crystal growth , chemistry , crystal (programming language) , stereochemistry , crystallography , materials science , inorganic chemistry , organic chemistry , physics , computer science , quantum mechanics , programming language
The structure of potassium dichromate (P‐1, Z = 4) consists of two layers parallel to (001), between which no crystallographic symmetry relation exists. These layers are nearly coincident with each other when rotated through 90° about c*. One question remained unanswered: do the crystals grow parallel to {001} with d(002) or d(001) layers? The pseudo‐fourfold axis does not run parallel to a crystallographic direction and acts only between two layers. This means that crystal growth parallel to {001} occurs in d(001) layers, which corresponds to the occurrence of one‐sided intergrowths on (00‐1). The layers are also nearly coincident with each other through pseudo‐twofold axes parallel to [110] and [‐110]. These axes do not act in the (100) or (010) projections. In the projections along the [110] and [‐110] directions, the lattice directions are then extended by a factor of approximately 1.414, and the formula units in the cell of the d(002) layer are doubled. This indicates a further possible growth mechanism. The theoretical growth forms of the crystals were calculated with the Fourier transform method of morphology.